Transcript The Cardiovascular System Chapter 9

The
Cardiovascular
System
Chapter 9
The Cardiovascular
System
 Includes:
 Heart
 Blood
vessels
 Blood
(and blood circulation)
The Heart
 Straddles the
midline
 Dorsal to the
sternum
 Base is
cranodorsally
 Apex is ventrally
to the left
The Heart

Acts as a pump to circulate blood throughout the
body to nourish tissues and remove waste
products.

Made of cardiac muscle (involuntary; striated)

Size varies with species

Located in the thoracic cavity
The Pericardium

Membrane that covers the heart

Composed of:

Fibrous pericardium (external layer)


Tough, fibrous sac surrounding serous layers
Serous pericardium (inner layers)

Parietal layer – lines the pericardium

Visceral layer – (a.k.a. – epicardium) – covers the
surface of the heart
The Pericardium

The pericardial space is the space between the
two serous layers of the pericardium

This space contains pericardial fluid

Pericardial fluid prevents friction between the heart
and the pericardium when the heart beats
Layers of the Heart

Heart wall has 3 Layers:

Epicardium – outer; visceral layer

Myocardium – middle layer; muscle
layer

Endocardium – innermost layer; lines
chambers and valves
LAYERS OF THE HEART:
Chambers of the Heart


There are 4 chambers within the heart:

2 craniodorsal chambers = atria

2 caudoventral chambers = ventricles
The heart is divided into right and left sides.

Interatrial septum divides atria

Interventricular septum divides ventricles
Chambers of the Heart

Atria receive blood and ventricles send blood.

Atria have thin walls and ventricles have thick
walls.

The right side of the heart receives blood from
body and sends it to the lungs to pick up O2.

The left side of the heart receives oxygenated
blood from lungs and sends it to the tissues.
Valves of the Heart

Atrioventricular valves (AV valves) lie between
each atria and ventricle.

Mitral valve – Left side; called bicuspid valve
because it only has two flaps/cusps.

Tricuspid valve – Right side; has three flaps

Flaps are attached to ventricular wall by chordae
tendineae.
Valves of the Heart

Semilunar valves (half-moon shaped) prevent
backflow of blood from arteries into ventricles.

Aortic semilunar valve is a 3-flapped valve
between left ventricle and aorta.

Pulmonary semilunar valve is located between
right ventricle and pulmonary artery.
Valves of the Heart
Valves of the Heart
Blood Circulation:
Systemic

Left ventricle

Aorta

Arteries

Arterioles

Capillaries

Venules

Veins

Right atrium
Blood Circulation:
Pulmonary

Right atrium

Right ventricle

Pulmonary artery

Lungs

Arterioles

Lung capillaries

Lung venules

Pulmonary veins

Left atrium

Left ventricle
Blood Circulation
Blood Vessels

Arteries carry oxygenated blood away from the heart back to
the body.

Walls are thick and muscular
***Exception = pulmonary artery***

Veins transport deoxygenated blood back to the heart.

Walls are thin and elastic

Valves prevent backflow of blood
***Exception = pulmonary vein***
Blood Vessels

As arteries branch out and become smaller, they become
arterioles.

Arterioles branch and become smaller into capillaries.

Capillaries have very thin walls and distribute O2 to tissues
while picking up CO2

Capillaries branch into larger structures called venules which
empty into larger structures called veins which return blood to
the heart.
Blood Vessels
Drop that beat!!!
Autonomic
Nervous System:
Parasympathetc:
mainly supply the SA & AV
Nodes, slows the heart rate,
reduces impuse conduction
Sympathetic: acts on the
SA & AV nodes to increase
the heart rate and impulse
condction
CONDUCTION SYSTEM
of electrical impulses
SINOATRIAL NODE is the pacemaker of the heart and
where the heartbeat originates and the rate is regulated
 located in the RA
 The impulses make the atria contract and force
blood into the ventricles
ATRIOVENTRICULAR NODE is in the right atrium near
the lower portion of the interatrial septum
 the electrical impulse from the SA node affects the
AV node, which then transmits the impulse to the
ATRIOVENTRICULAR BUNDLE (BUNDLE OF HIS)
 this is located in the interventricular septum
 the ventricles now contract as the impulse is carried
 throughout the ventricles via the PURKINJE FIBERS
The Cardiac Cycle

Atria contract in unison; ventricles contract in
unison

As one group contracts, the other relaxes.

Atrial contraction sends blood into ventricles
through bicuspid and tricuspid valves.

While this is occurring, the semilunar valves close

Ventricles relax at this time
The Cardiac Cycle

Ventricular contraction sends blood through the
semilunar valves and into the aorta and
pulmonary artery.

While this is occurring, the bicuspid and tricuspid
valves close

The atria relax, allowing blood to enter from the
vena cava and pulmonary veins.
The Cardiac Cycle

Systole


Part of the cardiac cycle
associated with contraction of
ventricles and atria and ejection
of blood into the arteries.
Diastole

Part of the cardiac cycle
associated with relaxation of atria
and ventricles and filling of the
chambers with blood.